The NICHD has provided support for the past five years to encourage the development of a system(s) for the early identification of HIV from blood (filter paper spots) of infants that are a few days old. This support has contributed to the development/refinement of a polymerase chain reaction (PCR) assay system that is relatively successful in the detection of HIV from the blood spots. This contract is for provide support for a research and development laboratory to further: l) develop innovative and reliable strategies for the early and very early diagnosis of HIV infection in infants with special emphasis on methods which may be applied to easily available and widely-collected samples of newborn blood (e.g. paper-absorbed dried samples like those collected on Guthrie cards); 2) study how such diagnostic methods may be used to monitor actual infection rates in infants, and to examine changes in natural history and ascertainment practices; 3) assess the impact of HIV-related therapies in infected pregnant women and/or their offspring based on the early detection of HIV infection in infants; 4) assist various investigations sponsored by the National Institutes of Health (NIH) in further studying certain issues that are relevant to the vertical transmission of HIV from infected pregnant women to offspring and that are relevant to the natural history of pediatric HIV infection and disease; and, 5) propose novel studies which will utilize the interaction of-basic biologic, epidemiologic, and clinical technologies and investigations to further elucidate the key issues concerning the natural history of vertically-transmitted HIV infection.